The present invention relates to a detection arrangement, a detection system incorporating the arrangement, and its method of operation.
The existence of a fire, for example, may be detected by various means, and it is known to employ a plurality of sensing elements that are responsive to different parameters. One such sensing element may be a carbon monoxide gas detector. In some installations it is required also to detect toxic gases, of which carbon monoxide may be one. Conventionally, separate fire and gas detection circuits are installed each having, for example, a carbon monoxide sensing element, each element being associated with a detection circuit that, to provide the required measurement accuracy, is sensitive to, say, a range of 0 to 40 parts per million (PPM) in the fire detection circuit and a range of 35 to 500 PPM in the gas detection circuit.
In other applications, such as overpressure and explosion detection, for example, two detection circuits may be provided, each of which has a pressure sensor, with the circuits having different levels of sensitivity for detecting, on the one level, a comparatively low overpressure, and, on the other level, a much higher pressure indicative of an explosion.
It is an object of the present invention to provide a simplified detection circuit.